Lubricating oil refining



July 21, 1936. J SHEPARD I 2,048,52I

LUBRICATING OIL REFINING Filed Jan. 11, 1933 INVENTOR Jamaajt. film Hard 45 a? ATI'ORINEY Patented July 21, 1936 UNITED STATES PATENT OFFICE LUBRICATIN G OIL REFINING ration of Indiana Application January 11, 1933, Serial No. 651,092

4Claims.

This invention relates to the refining of lubricating oil and it pertains more particularly to the use of special solvents for separating paraflinic from naphthenic constituentsof' mixed base lubricating stocks whereby the viscosity index of the finished lubricant is improved.

My process relates to the use of a selective solvent such as beta beta dichlorethyl ether, and the object of my invention is to improvethe efiiciency of solvent extraction processes in which such a solvent is used. A further object is to increase the yield of my high viscosity index oil from any given stock. A further object is to reduce the amount of solvent required per gallon of finished oil produced. A further object is to avoid emulsion difficulties, and particularly to avoid'the conventional step of soap removal after the neutralization which follows a preliminary acid treatdenser'coils wherein the solvent is recovered. A

further object is to reduce the cost of neutralization as well as the cost of diluent, oil, etc. A further object is to provide an improved lubricating oil which will be characterized by a low ash and a high color stability, and which will have a minimum tendency to form emulsions (high demulsibility) Other objects will be apparent as the detailed description of my invention proceeds.-

In practicing my invention, I first give my lubricating stock a light acid treatment and separate the sludge and tarry matter therefrom. I then neutralize the sour oil with ammonia and I do not attempt to wash out the ammonia soaps but leave them in the oil solution. I next extract the oil with about two and one-half to three volumes of beta beta dichlorethyl ether or the like, separating the extracted layer from the'rafiinate layer, and removing the solvent from both layers. Finally, I treat the raflinate with clay to obtain the desired color and to remove any undesirable soaps which may have remained in the oil. It should be particularly noted that in this process the soaps formed from the sulfonic and otheroil soluble acids (mahogany acids) in the neutralization following the preliminary acid treat, are thrown down with the extract in the solvent extraction step so that I avoid the removal of ammonia soaps I will describe the invention as applied to the treating of a heavy distillate lubricating stock which has been dewaxed and which has a viscosity of about'80 seconds Saybolt at 210 F. It should be understood, however, that the invention is equally applicable to stocks which have not been dewaxed, to residual stocks and, in fact, to any lubricating oil stock prepared from mixed base naphthenic or asphaltic crudes. when a residual stock is used, itmay be desirable to remove the bulk of the asphaltic material by a preliminary precipitation thereof with propane, or by a heavier acid treat than that which is hereinafter described. Such expedients will be apparent to those skilled in this art.

As the extracting solvent I prefer to use beta beta dichlorethyl ether which will hereinafter, for the sake of simplicity, be referred to as ether". I may, however, use other solvents, such as chloraniline, nitrobenzene, aniline, paraldehyde, fur-.

fural, cresol, pyridine, phenyl acetate, ethyl chloracetate, isopropyl ether, furfuralcohol, etc., or mixtures thereof.

The oil stock from storage tank It is forced by pump I I through mixer l2, where it is intimately If and mixed with acid supplied from acid tank l3 and 20 introduced by pump 14. This acid treatment is of a preliminary nature and it serves to remove a large. amount of tarry matter and to therebymaterially reduce the necessary amount of extracting solvent. I prefer to use about one-half to three-fourths pound of 93% acid per gallon of oil treated, but it should be understood that these proportions and concentrations may vary someor it may be an upright tank with a conical bot-- tom. It may be preferable to effect s udge separation by centrifugal means and it should be understood that I may use a centrifuge instead of a settling tank for continuously removing the sludge from the sour oil.

The sour oil from receiver l9is forced by pump 20 to neutralizer tower 2| wherein it passes countercurrent to ammonia vapors introduced at the base of the tower through pipe 22. The amount of ammonia introduced is just suflicient to neutralize the sour oil and I may,'in fact, eliminate the neutralizer tower 2| entirely and merely blow the ammonia into the base of receiver 19. 11 prefer, however, to efiect continuous neutralization in the manner hereinabove described, the neutralized oil being passed by pipe 23 to reeeiver 24.-

The neutralized oil from receiver 24 is forced by pump 25 into mixer 26 wherein it is intimately mixed with about two and one-half to three volumes of ether introduced from storage tanks 21 by pump 28. It is essential that intimate contacts be obtained between the solvent and the separation of parafiinic from naphthenic components the mixture must be cooled preferably to about 40 or 50. F'., and I therefore pass the mixture through cooler 29 prior to introducing itinto raflinate-extract separator 30. This separator may be of the simple gravity type or r it may consist of a centrifuge or equivalent means for separating the heavy. ether extract from the lighter raflinate phase. Ordinarily the railinate and extract separate readily, but if there is a tendency toward emulsion formation, the centrifuge will solve the difiiculty. The extract is discharged through pipe 3| to a suitable recovery system and the railinate is discharged into receiver 32 from whichdt is picked up by pump 33 and formed into stripping still 34 for removing the solvent from the oil. The "ether" vapors are condensed-in condenser 35 and returned by pipe 36 to storage tanks 21. In order to prevent de-' composition of the ether" in condensing coils traces of solvent from the oil in the still I prefer Ifintroduce a small-amount of ammonia gas thereto through pipe 31. To remove the last A to strip vvithsteam which may be introduced through pipe 38. The water which is thus mixed with the solvent may be removed therefrom by a suitable water trap 39.

The oil from the stripping still is next forced by pump 40 to contact clay filter 4|, where the oil is percolated through fullers earth and at a temperature of about 250-300 F. Altemativeiy, I may contact the oil with about one-half to threefourths pound of clay per gallon at about 540 I".

prior to the solvent extraction step. flcial effects of this preliminary acid treatment may be obtained even if the oil is extracted with I the ether" prior to neutralization, but such a process would be objectionable because of the corrosion which would be encountered throughout" theextraction system. In accordance with conventional practice, these corrosion difliculties would ordinarily be overcome by neutralizing the 7 .sour oil with caustic, using about 32 pounds of soda aslr per thousand gallons of oil stock charged.

After such neutralization. it is necessary to extract the sodium mahogany soap from the neu-' tralized oil, which step requires about 107 gallons of green acid soap per thousand gallons of oil stock charged, causing a loss of 2-10% of the oil, or which requires a large amount of expensive alcohols or equivalent solvents. I avoid entirely the use of the green a'cid soap orequivalent-solizing reagents by using ammonia instead of-soda ash. It has heretofore been considered impossible to obtain satisfactory neutralizationwith ammonia because the ammonium soaps cause emul-.

sion difiiculties, and because the ammonia neu- I have disand I have found that this separation may be readily effected without emulsion difliculties. Furthermore, I have found that when theraflinate is finished with clay, the oil has as good a color stability as oil produced from soda neutralized and washed stock. It will thus be seen that by ammonia neutralization I decrease the cost of the neutralizing agent, I eliminate entirely the steps of hot water washing and mahogany soap removal, and I facilitate handling. In addition to all of these advantages I find that the process hereinabove described gives a 2-10% higher yield than can be"obtained with the conventional soda neutralization, a large part of this saving probably being due to the elimination of 15 the hot water washing step in the extraction of mahogany soap.

The ammonia neutralization prior to solvent extraction not only minimizes corrosion in the solvent extraction system, but it reduces the 20 amount of ammonia which would be introduced by pipe 31 into condenser coils 35. In other words, the use of ammonia neutralization minimizes the hydrolysis or decomposition of the ether. As a matter of fact, I have found that 25 the solvent loss in my ammonia neutralization process is about one-half to one-third the amount heretofore obtained and is reduced to about .01%.

While I have described in detail a preferred embodiment of my invention, it should be un- 80 derstood that I do not limit myself to the details hereinabove set forth except as defined by the following claims which should be construed as broadly as theprior art will permit.

( I claim:

1. The process of refining mineral oils which comprises subjecting mineral oil stocks to treatment "with sulfuric acid, separating the acid sludge from the oil, neutralizing the acid treated oil with ammonia, immediately (without the intervention of a water washing step) extracting the ammonia neutralized oil with a selective solvent of the type used for separating paramnlc from naphthenic components, separating an extract phase from a raflinate phase and removing solvent from each phase respectively.

2. Ijhe process of refining mineral lubricating oils which comprises treatingsaid oils with a small amount of sulfuric acid, neutralizing said treated oil with ammonia, and without removing oil soluble or water soluble suifonic compounds from the neutralized oil, extracting said oil with a solvent comprising at least one of the class which consists of beta beta dichlorethyl ether, chloraniline, nitro benzene, furfural, cresol, pyridine and furfuraloohol, separating a raflinate from an extract phase and separately removing solvent from each phase respectively.

3. The method of refining mineral lubricating oils which comprises treating said oils with an amount of sulfuric acid approximately equivalent one-half to three-fourths pound of 93% sulvent, and Imaterially reduce the cost of neutralfuric acid per gallon of oil, neutralizing said acidr treated oil with ammonia, and immediately extracting said neutralized oil with a selective solvent of the type used for separating paraflinic from naphtheniccomponents, separating said paraflinic from said naphthenic components and removing solvent from each component.

,4. The process of claim 1 wherein the selective solvent is dichlorethyl ether.

. w JAMESH.SHEPARD. 

